Molecular evidence for early deuterostome origins of ovarian cell types and neuroendocrine control of reproduction

Oogenesis requires complex interactions between germline and somatic cell types in the ovary. How did these cell types and their signaling interactions evolve? Here we use the sea star Patiria miniata as a non-chordate deuterostome representative to define the ovarian cell type toolkit in echinoderms. Sea stars continuously produce millions of new oocytes throughout their lifespan, making them a practical system to understand the mechanisms that drive oogenesis from a biomedical and evolutionary perspective. We performed scRNA-seq combined with high-resolution 3D imaging to reveal the ovarian cell types and their spatial organization. Our data support the presence of putative oogonial stem cells, granulosa-like, and theca-like cells, which display similarities with their mammalian counterparts. We also describe possible signaling interactions between somatic and germ line cells. Lastly, our data may suggest an intrinsic ovarian neuroendocrine system which could potentially regulate oogenesis. Paganos et al provide evidence suggesting that sea stars may share ancient ovarian cell types and signaling systems with mammals, offering new clues to how egg development and reproductive regulation evolved across animals.